The present invention relates to a color image forming apparatus in which a plurality of developing units are disposed around the circumferential surface of an image forming body.
Both a drum-shaped image forming body and a belt-shaped image forming body are used for the image forming apparatus. In the case where the former image forming body is adopted, the profile is fixed. On the other hand, in the case where the latter image forming body is adopted, the profile is variable, so that the degree of freedom can be increased when the apparatus is designed.
When the belt-shaped image forming body is adopted, it is possible to provide a wide flat portion of the belt-shaped image forming body, which is advantageous to dispose a plurality of developing units. Therefore, the belt-shaped image forming body is widely used for color image forming apparatus.
When an image forming apparatus is designed, either a drum-shaped image forming body or a belt-shaped image forming body is selected from the viewpoint of the layout of the apparatus. When the belt-shaped image forming body is adopted, it is provided to the apparatus either longitudinally or laterally. In this case, a group of developing units and a cleaning unit are provided in the periphery of the belt-shaped image forming body. Therefore, when they are integrated into a process cartridge, the dimensions of the process cartridge are increased, so that it is difficult to attach the process cartridge to the apparatus or detach it from the apparatus.
When the aforementioned large-scale cartridge is attached to or detached from the apparatus, toner or dust adhered to the cartridge drops on the optical image exposure system, so that there is a possibility that the performance of the optical system is lowered.
The aforementioned problems are solved by the apparatus of the present invention. The first object of the present invention is to provide a color image forming apparatus characterized in that: a jam clearance operation is easily carried out; the process cartridge is easily attached to and detached from the apparatus; and toner leakage can be prevented so that the optical image exposure system is kept clean.
In a color image forming apparatus, image processing is carried out with regard to a plurality of colors. Therefore, the color image forming apparatus includes: a plurality of developing units, each of which has the function of developing a single color, that are provided around the peripheral portion of the image forming body; and a plurality of toner containers that supply toner to the developing units.
On the other hand, since the maintenance operations must be frequently conducted on the developing units, the developing units are integrated into a process cartridge together with the image forming body and the cleaning unit. Consequently, each time the cartridge is attached to and detached from the apparatus, the developing units must be connected with and disconnected from the toner containers.
In order to prevent toner leakage, the structure of the connecting section between the developing unit and the toner container is complicated, so that it is difficult to handle the developing units. Further, when the developing units are disconnected from the toner containers, toner leakage can not be avoided. Therefore, the inside of the apparatus is stained with toner, and the quality of formed images is deteriorated.
In order to solve the aforementioned problems, a countermeasure is taken in which the toner containers and developing units are integrated into one unit and the unit is installed in the process cartridge. However, the aforementioned countermeasure is disadvantageous in that: the dimensions of the process cartridge are increased; and the cartridge must be taken outside each time toner is supplied, and therefore the working efficiency can not be improved.
The aforementioned problems are solved by the present invention. The second object of the present invention is to provide a color image forming apparatus in which a complicated connection mechanism for toner supply is not required and toner can be supplied very easily, for example, toner can be supplied when the process cartridge is moved a little.